1‑Phenyl-3-(pyrid-2-yl)benzo[<i>e</i>][1,2,4]triazinyl: The First “Blatter Radical” for
Coordination Chemistry

A neutral air- and moisture-stable
N,N′-chelating radical ligand, 1-phenyl-3-(pyrid-2-yl)­benzo­[<i>e</i>]­[1,2,4]­triazinyl (<b>1</b>) was synthesized and
characterized by electron paramagnetic resonance spectroscopy, X-ray
crystallography, and magnetic measurements. Subsequent reaction of <b>1</b> with Cu­(hfac)<sub>2</sub>·2H<sub>2</sub>O (hfac = hexafluoroacetylacetonate)
under ambient conditions afforded the coordination complex Cu­(<b>1</b>)­(hfac)<sub>2</sub> in which the radical binds to the metal
in a bidentate fashion. Magnetic susceptibility data collected from
1.8 to 300 K indicate a strong ferromagnetic metal-radical interaction
in the complex and weak antiferromagnetic radical···radical
interactions between the Cu­(<b>1</b>)­(hfac)<sub>2</sub> units.
Detailed computational investigations support this assignment. Radical <b>1</b> is a new addition to the growing library of 1,2,4-triazinyl
radicals and the first member of this family of paramagnetic species
synthesized specifically for coordination purposes.